Operating Leases (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Operating Leased Assets [Line Items]
Due to Related Parties, Current	$ 0		$ 0		$ 100
Operating Leases, Rent Expense	0	$ 800	800	$ 2,800
Payments for Repurchase of Common Stock			14,678	30,858
related party payment for terminal purchase		4,875	0
Related Party
Operating Leased Assets [Line Items]
Operating Leases, Rent Expense	0	767	813	2,651
Terminal Facilities
Operating Leased Assets [Line Items]
Operating Leases, Rent Expense	500	900	1,600	3,000
Terminal Facilities | Related Party
Operating Leased Assets [Line Items]
Operating Leases, Rent Expense	$ 466	$ 833	$ 1,397	$ 2,753